2x (3x+5) + 3 (3x+5) = ax^2+bf+c in the equation above a, b, and c are constants. If the equation is true for all values of x what is the value of b

2x (3x + 5) + 3 (3x + 5) = ax² + bf + c

2x. 3x + 2x. 5 + 3.3x + 3.5 = ax² + bf + c

6x² + 10x + 9x + 15 = ax² + bf + c

6x² + 19x + 15 = ax² + bf + c

6x² = ax²

6 = a

19x = bf

15 = c

As the question says, b is constant, so he can't be a variable, so he only can be 19 and f be x

19x = bf

19 = b

x = f